Is a P11D mandatory even if there are no benefits to report?

I have a client that submitted a P11d showing a benefit in kind by mistake. I spoke to HMRC and had the benefit taken out and thought nothing more of it. However, the client has been in touch to say they have now received late filing penalties going back 2 years for the last 2 P11D returns 09/10 & 10/11. Is there anything that can be done? There were no benefits to declare in either year.